1. Field of the Invention
The present invention relates to an optical disk device for recording or reproduction of signals on or from disk-type recording media such as DVD (Digital Video Disk). More specifically, the present invention relates to a small and/or thin optical disk device used as a peripheral device of a home video appliance or a computer.
2. Description of the Related Art
The typical optical disk devices represented by CD-ROM drives have increasingly become smaller and thinner so as to be installed in notebook type personal computers.
In general, when an optical disk device is intended to be made smaller and thinner, it is difficult to secure a sufficient clearance such as space for mechanical vibration or actuation because space for mounting elements which constitute the optical disk device is limited.
One exemplary product of conventional small, thin optical disk devices whose space for mounting the elements is limited is a CD-ROM drive having a height of 12.7 mm, which is incorporated in notebook type personal computers, and has already been put on the market.
The CD-ROM drive having a height of 12.7 mm includes an optical pickup, a disk motor having a disk clamp mechanism, a base chassis which supports the optical pickup and the disk motor, a tray which includes circuits and the like therein and supports the base chassis via a damper, an exterior package which supports the tray which is slidable back and forth, and a wiring element which connects the optical pickup and a main body.
Recently, DVDs having a recording capacity which is eight times as large as that of CDs have received attention. DVD players employing an optical disk which is based on a DVD format and DVD-ROMs have just been distributed in the market.
In general, if the optical axis of an object lens is tilted with respect to the recording surface of an optical disk, wave aberration is generated in proportion to the third power of a numerical aperture (NA) of the optics. In DVD, the numerical aperture of the optics of the optical pickup, which performs high-density recording and reproduction, is set to be 0.6 so as to be larger than the numerical aperture of CDs (0.45). Thus, even a slight tilt with respect to the optical axis causes a great jitter.
Therefore, the optical disk devices for DVDs require a mechanism for adjusting a tilt angle (i.e., an angle between the optical axis of the optical pickup and the recording surface of the disk) in order to eliminate jitters. The tilt angle can be adjusted by tilting the disk motor, by tilting the optical pickup or by tilting the guiding axis. The mechanism which tilts the disk motor or the optical pickup has a low adjusting sensitivity, whereas the mechanism which tilts the guiding axis has a comparatively high adjusting sensitivity.
An optical disk device having such a function is disclosed in the previously filed Japanese Laid-Open Publication 10-116479. In the optical disk device disclosed in Japanese Laid-Open Publication 10-116479, the ends of main and minor shafts adjacent to the outer periphery of the optical disk, which support the movement of the optical pickup in the radial direction of the disk, are adjustable in a direction generally perpendicular to the surface of the optical disk. Also, the radial tilt angle and the tangential tilt angle are adjusted respectively by the fluctuation of the major shaft and the minor shaft where the optical pickup is kept above at the position in the middle of the radius of the optical disk.
The above described CD-ROM drive, having a height of 12.7 mm, does not have the above described mechanism for adjusting the tilt angle. Therefore, such an optical disk device has a drawback of being unable to perform recording and reproducing for recording media which have high density and large capacity, such as DVDs.
An object of the present invention is to solve the above described problems by providing a small, thin optical disk device which can be mounted in notebook computers.